1. Patients needing general anesthesia to undergo MRI;
2. Children with Down syndrome or other underlying syndromes;
3. Patients unable to undergo MRI due to claustrophobia;
4. Patients with underlying skeletal disorders, including prior fractures of the knees;
5. Patients with (juvenile rheumatoid) arthritis;
6. Patients with metallic implants and foreign bodies in and around the knee joint (although they may be MRI compatible; image artefacts).

- mec approval received

yes

- multicenter trial

no

- randomised

no

- group

Parallel

- Type

Single arm

- Studytype

observational

- planned startdate

1-dec-2012

- planned closingdate

1-dec-2017

- Target number of participants

62

- Interventions

2-3 MRIs will be taken of both knees. If cartilage damage is observed, the patient will undergo 1 or 2 additional MRIs.

- Primary outcome

The main study endpoint is cartilage damage as determined by MRI, compared to a baseline MRI. The amount of important structural components of cartilage (e.g. collagen and glycosaminoglycans) will be measured and mapped quantitatively, for a sensitive and objective quantitative outcome measure of cartilage quality.

1. Baseline MRI: Within first week of diagnosis of ALL;
2. Second MRI: After 8 weeks (±1 wk) of ciprofloxacin exposure;
3. In medium risk and high risk (ALL-11 protocol grading): Within 2 weeks after discontinuation of ciprofloxacin treatment;
4. If cartilage damage is present: 1 MRI yearly up to one year after discontinuation ALL treatment.

Ciprofloxacin has been associated with skeletal safety concerns and is therefore formally contra-indicated (with some exceptions) in patients <18 years of age. During the treatment of ALL, patients receive ciprofloxacin for microbiological prophylaxis. Currently, therapeutic doses of ciprofloxacin are used for prophylaxis due to a lack of information on optimal dosing in the prophylactic setting. The drug is given for prolonged periods of time due to recurrent neutropenia and increased risk of infections. However the musculoskeletal safety of ciprofloxacin has not been studied in this setting. Irreversible cartilage toxicity has been observed in animal studies, especially in weight baring joints. The incidence of reported clinical complains of the musculoskeletal system in children treated with quinolones varies between 0-23%. In addition, patients are simultaneously treated with glucocorticoids, which are known to induce osteonecrosis and osteopenia. Hence this combination might result in synergistic skeletal toxicity in these patients.